The conventional techniques of crop and plant delivery in agriculture include placing seed directly in the ground either by hand or machine planting. Either of these techniques may be incorporated in a broadcast or precision sowing method. Such seed is commonly planted untreated or sometimes treated to a brief dip in a fungicide or covered with a layer of dry diatomaceous earth (or other appropriate material) with or without dried preparations of microorganisms. Additionally, seed may be coated with compounds (such as methyl cellulose or sodium alginate) in which a solvent is required for initial coating of the seed. Subsequently, the solvent is evaporated or dried off to result in a final coating that is not saturated or complexed ionically. Saturation is a concept incorporated herein which is defined to be where no more solvent or liquid can be absorbed or retained.
As an alternative, such seeds, treated or untreated, are first sown in greenhouse or nursery beds. Plantlets are raised to a particular size before transplanting to the field. Conventional methods of seed planting and transplant production are well known and described in the literature. See, e.g., J. H. Martin and W. H. Leonard, "Principles of Field Crop Production," (Macmillan Company, N.Y., 1949); J. H. MacGillivray, "Vegetable Production," (Blakiston Co., N.Y., 1953); and R. L. Carolus, "Possibilities with the Use of Pelleted Seed" (Ohio Veg. and Potato Growers Assoc., Ann. Proc. 34: 56062, 1949).
The conventional technique of delivery of adjuvants that affect plant, insect, fungus, bacteria, animal and other growth is to apply the adjuvant physically separate from the plant seed. Plant nutrients, pesticides, beneficial microorganisms and other biologically active compounds are applied (1) before the time of seed planting by soil incorporation or by placement on top of the soil, (2) to the soil as the seeds are being planted, or (3) after the seeds are planted by soil incorporation, spray application, or other physical means. Conventional methods are well known and described in the literature. See, e.g. J. Janick, R. W. Schery, F. W. Woods, V. W. Ruttan, "Plant Science," (W. H. Freeman, San Francisco, 1974); and "Western Fertilizer Handbook," (Institute Printers and Publishers, Danville, Ill., 1975).
A major limitation to these conventional methods is the requirement to plant the seeds and deliver the adjuvants separately, usually by way of separate passes through the field with the tractor. This is costly as well as harmful since it increases the incidence of soil compaction due to the tractor weight.
An additional limitation is that the adjuvant is not precisely applied to the specific points in the field where the adjuvant reacts with the seed or its microenvironment. For beneficial microorganisms, the specific application point is at the seed, where developing roots will interact with the applied microorganisms. The same application point is suggested for herbicides to limit weed competition, nematicides to control root invading nematodes, insecticides to control both root and upper plant-attacking insects, nutrients to nourish the developing plant, as well as other adjuvants to benefit seed establishment and growth. Because adjuvant application by conventional methods is non-precise much of the adjuvant is wasted or non-effective.
A further limitation is that many adjuvants are volatile, flammable, toxic or otherwise environmentally hazardous, and therefore, pose difficulty in handling and application for both the operator and the environment.
A still further limitation is that conventional methods do not provide a system for delivery of a seed that has undergone seed inbibition (priming) but which seed has not then been subsequently dried.
It has been recognized that some of these difficulties may be overcome by incorporating some of the adjuvants, specifically micro-organisms, in a dry covering around the seed. See, e.g., T.V. Suslow and M. N. Schroth (Phytopathology 72: 199, 1982). This technique provides for direct application of microorganisms with the seed. However, the process to coat the seed requires that both the seeds and microorganisms be dried, a process that often results in decreased seed germination rates and death of a majority of the microorganisms.
It has also been recognized that the adjuvants can be applied to the seed in the form of a wet seed coating (water added to facilitate the coating process), which coating is subsequently dried to form a less than saturated seed coating around the seed. See, e.g., Scott (U.S. Pat. No. 2,967,376). However, the process to coat the seeds requires that both the seeds and adjuvants be subsequently dried, a process that damages the seed if priming has occurred.
Another technique which has found some use is fluid drilling. Pre-germinated seeds are delivered, occasionally with microorganisms or other additives, in a thick slurry by means of special implements. See, e.g. Taylor, J. D. and C. L. Dudley, "Rhizobium . Inoculation of Dwarf Beans", Nat. Veg. Res. Sta. U.K. 28th Ann. Rep. p. 105 (1977); Hardaker, J. M. and R. C. Hardwick, "A Note on Rhizobium Inoculation of Beans", Expl. Agric. 14:17-21 (1978); Entwistle, A. R. and H. L. Munasinghe, "The Control of White Rot (Sclerotium cepivorum) in Fluid-drilled Salad Onions" J. Hort. Sci. 56:251-54 1981). However, this method does not allow for singulation of seeds in a deliverable, saturated hydrogel capsule. Further, this method does not permit precise seed planting. Seed viability is often reduced, and specialized planting equipment is required.
A further technique which has been suggested for delivery of seeds is to mix the seeds in a hydrogel of a high molecular weight hydrophilic polymer. The polymer, preferably containing a basic carboxylic acid salt residue, is cross-linked. The resultant mixture is combined with water to form a non-sticky hydrogel. The hydrogel, combined with seeds, is poured or dribbled along a row of soil to affect seed germination. See, e.g., S. Kitamura, M. Watanabe, M. Nakayama, and S. Ouchii (Japanese Patent 1983 33508, assigned to Sumitomo Chemical Co.). However, this process is similar to fluid drilling and does not allow for seed singulation nor allow for precision seed planting. Furthermore, the hydrogel/seed mixture is not a unitized, easily handled package that can be planted using existing seed handling and planting equipment.
It has been suggested that adjuvants be microencapsulated to provide controlled release of the adjuvants, thereby lengthening the time of activity. See, e.g., T. J. Roseman and S. Z. Mansdorf, "Controlled Release Delivery Systems" (Marcel Dekker, Inc., N.Y., 1983. However, this technique does not provide for precision placement of the adjuvants where they will be most effective.
Thus, an object of this invention is to provide a technique whereby seeds are advantageously combined with adjuvants prior to planting.
Another object of this invention is to control germination and development of the seeds.
Yet another object of the invention is to provide a saturated medium to deliver the seeds together with adjuvants.
A further object of the invention is to reduce the amount of handling and time required for delivery of seeds and adjuvants to field, nursery, or greenhouse.
A still further object of the invention is to provide a delivery method for seeds and adjuvants.
A final object of the invention is to control the release of the seeds and adjuvants.